1. Field of the Invention
This invention relates to arrangements for controlling sidetone in telephone sets.
2. Description of the Prior Art
Sidetone in a two-wire telephone set is the speech or other signals heard in the set's receiver in response to speech or other signals being impressed on the set's transmitter. It is known that an excessive sidetone level causes a speaker to lower his or her voice level while a low sidetone level causes a speaker to raise his or her voice level. It is also known that three-port hybrid circuits can be used to achieve antisidetone. Furthermore, it is known that these circuits can be modified to provide a small but fixed percentage of sidetone coupling between transmitter and receiver, where the coupling is sufficient to cause the average telephone user to speak at a desired level. Telephone users, however, are not identical, and consequently there still are users who speak too loud or too low.